U.S. patent application number 11/327372 was filed with the patent office on 2006-07-20 for wheel support bearing assembly.
This patent application is currently assigned to NTN CORPORATION. Invention is credited to Katsumi Furukawa, Kazuhisa Shigeoka.
Application Number | 20060159377 11/327372 |
Document ID | / |
Family ID | 36683969 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060159377 |
Kind Code |
A1 |
Shigeoka; Kazuhisa ; et
al. |
July 20, 2006 |
Wheel support bearing assembly
Abstract
To provide a wheel support bearing assembly designed to avoid an
ingress of foreign matter from an area, where a sensor is fitted,
into the inside of the bearing assembly. The wheel support bearing
assembly includes an outer member (1) adapted to be secured to a
vehicle body structure, an inner member (2) adapted to support a
vehicle wheel, and circular rows of rolling elements (3) interposed
between the outer and inner members (1,2). A sensor cap (13) is
provided for closing an inboard end of the outer member (1) and has
an insert nut (15) embedded therein. The sensor cap (13) is also
provided with a reduced diameter hole (23), in which an elastic
sealing member (25) is interposed under interference fit between it
and a deep end face of the insert nut (15).
Inventors: |
Shigeoka; Kazuhisa;
(Iwata-shi, JP) ; Furukawa; Katsumi; (Iwata-shi,
JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700
1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
NTN CORPORATION
Osaka
JP
|
Family ID: |
36683969 |
Appl. No.: |
11/327372 |
Filed: |
January 9, 2006 |
Current U.S.
Class: |
384/448 |
Current CPC
Class: |
B60B 27/0005 20130101;
B60B 27/0073 20130101; F16C 41/007 20130101; F16C 19/186 20130101;
F16C 2326/02 20130101; B60B 27/0068 20130101; B60B 27/0084
20130101; B60B 27/0094 20130101; F16C 33/723 20130101 |
Class at
Publication: |
384/448 |
International
Class: |
F16C 32/00 20060101
F16C032/00; F16C 41/04 20060101 F16C041/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2005 |
JP |
2005-010304 |
Claims
1. A wheel support bearing assembly comprising: an outer member
adapted to be secured to a vehicle body structure and having an
inner peripheral surface formed with a plurality of raceways
defined therein; an inner member adapted to support a vehicle wheel
and having raceways defined therein in alignment with the
respective raceways in the outer member; corresponding circular
rows of rolling elements each row interposed between the raceway in
the outer member and the raceway in the inner member; a sensor cap
secured to an inboard end of the outer member to close an inboard
opening of the outer member; an insert nut embedded in a portion of
the sensor cap, which is made of a synthetic resin, with its one
open end opening at outer surface of the sensor cap, a sensor
insertion hole being defined in the sensor cap in a juxtaposed
relation with the insert nut; a sensor support member carrying a
sensor arranged on an outer surface of the sensor cap with the
sensor inserted into the sensor insertion hole and having a bolt
insertion hole defined therein; a sensor fastening bolt inserted
into the bolt insertion hole and then threaded into the insert nut
to fix the sensor support member to the sensor cap; and a pulsar
ring provided on the inner member so as to confront the sensor and
cooperable with the sensor; wherein the sensor cap has a reduced
diameter hole defined therein at a location adjacent a deep end
face of the insert nut so as to communicate between an internally
threaded bore of the insert nut and the inside of the sensor cap,
which reduced diameter hole has an inner peripheral surface formed
with a counter surface confronting the deep end face of the insert
nut; and wherein a sealing member having an elasticity is
interposed between the counter surface of the reduced diameter hole
and the deep end face of the insert nut under interference fit
therebetween for thereby sealing.
2. The wheel support bearing assembly as claimed in claim 1,
wherein the sensor is a rotation sensor for detecting revolution of
the inner member relative to the outer member.
3. The wheel support bearing assembly as claimed in claim 1,
wherein the sealing member is a rubber ball.
4. The wheel support bearing assembly as claimed in claim 2,
wherein material for the rubber ball is chosen from the group
consisting of nitrile rubber, fluorocarbon rubber, acrylic rubber
and hydrogenated nitrile rubber.
5. The wheel support bearing assembly as claimed in claim 2,
wherein the reduced diameter hole has a spherical inner surface and
is formed in part in a thick walled portion of the sensor cap,
positioned at a location aligned with the deep end face of the
insert nut, and in part in an annular protrusion protruding
rearwardly of the thick walled portion and having an inner
peripheral surface thereof defining the counter surface.
6. The wheel support bearing assembly as claimed in claim 1,
wherein the sensor cap has an axially extending cylindrical wall
made of the synthetic resin and also has a metallic reinforcement
ring within the axially cylindrical wall.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to a rolling bearing
assembly for rotatably supporting a vehicle wheel and, more
particularly, to the wheel support bearing assembly incorporating a
rotation sensor mounted on a sensor cap closing one open end of the
bearing, for detecting the number of revolutions of the vehicle
wheel.
[0003] 2. Description of the Prior Art
[0004] Some of the vehicle wheel bearing assemblies are known, in
which a rotation detecting device for detecting the number of
revolutions of vehicle wheels is incorporated for the purpose of
performing various controls, for example, for controlling an
automobile anti-skid control system, also known as an anti-lock
brake system (ABS), and a traction control system (TCS). This
rotation detecting device includes a pulsar ring fitted to a
rotatable member of the bearing assembly for rotation together
therewith and a sensor fitted to a stationary member of the same
bearing assembly. In the case of a vehicle driven wheel having the
sensor incorporated on an inboard side, the sensor is generally
installed in a sensor cap used to close one of opposite open ends
of an annular bearing space delimited between the rotatable and
stationary members. See, for example, the Japanese Laid-open
Utility Model Publication No. 7-31539, the Japanese Laid-open
Patent Publication No. 9-61443 and the Japanese Patent No.
3440800.
[0005] The wheel support bearing assembly, in which the sensor is
installed in the sensor cap, is illustrated in FIGS. 3 and 4. The
wheel support bearing assembly shown therein is of a structure
designed to rotatably support a vehicle driven wheel and includes
an outer member 31 rigid with a vehicle body structure, and an
inner member 32 having a vehicle wheel secured thereto for rotation
together therewith, and a plurality of, for example, two, rows of
rolling elements 3 accommodated within an annular bearing space
delimited between the inner and outer members 31 and 32 and spaced
a distance axially from each other. The inner member 32 is made up
of an hub axle and an inner race forming segment 35 fixedly mounted
on an inboard end of the hub axle as shown in FIG. 3. A pulsar ring
39 is secured to the inner race forming segment 35 and, on the
other hand, a sensor cap 43 made of a synthetic resin is secured to
the outer member 31 so as to close an inboard open end of the
annular bearing space between the outer and inner members 31 and
32.
[0006] The sensor cap 43 is provided with the sensor 40 therewith
and arranged so as to confront the pulsar ring 39 in a direction
axially of the bearing assembly, and the sensor 40 cooperates with
the pulsar ring 39 to define a rotation sensor unit 38. A portion
of FIG. 3 indicated by the phantom circle IV is shown on an
enlarged scale in FIG. 4. As shown therein, the sensor 40 is fitted
to a sensor support member 49 and is fixedly inserted into a sensor
insertion hole 46 defined in the sensor cap 43 with the sensor
support member 49 arranged on an outer surface of the sensor cap
43. When the sensor support member 49 is firmly fastened to the
sensor cap 43 by means of at least one sensor fastening bolt 52,
the sensor 40 can be firmly locked to the sensor cap 43. This
fastening of the sensor support member 49 with the sensor fastening
bolt 52 is carried out by threading the sensor fastening bolt 52
into an insert nut 45 embedded in the sensor cap 43.
[0007] It has, however, been found that the foregoing construction
has the following problem associated with an undesirable ingress of
foreign matter into the bearing assembly. Specifically, foreign
matter such as, for example, muddy water may ingress through slight
gaps between the internal threads of the insert nut 45 and the
sensor fastening bolt 52 and surfaces of contact between the sensor
fastening bolt 52, the sensor support member 49 and the sensor cap
43 and then into the interior of the bearing assembly, and
particularly the annular bearing space, through an axial bottom
hole 42 defined in the sensor cap 43. The foreign matter such as,
for example, muddy water may also ingress through surfaces of
contact between the insert nut 45 and a portion of the sensor cap
43 made of the synthetic resin. Once such ingress of the foreign
matter into the interior of the bearing assembly occurs, not only
will the lifetime of the bearing assembly be lowered, but also the
pulsar ring may possibly be deteriorated.
SUMMARY OF THE INVENTION
[0008] In view of the foregoing, the present invention has for its
object to provide an improved wheel support bearing assembly
designed to avoid an undesirable ingress of foreign matter such as,
for example, muddy water, into the interior of the bearing assembly
through gaps present in the vicinity of the threaded hole for
securement of the sensor, the sensor support member and/or the
sensor fastening bolt.
[0009] In order to accomplish the foregoing and other objects and
features, the present invention provides a wheel support bearing
assembly including an outer member adapted to be secured to a
vehicle body structure and having an inner peripheral surface
formed with a plurality of raceways defined therein, an inner
member adapted to support a vehicle wheel and having raceways
defined therein in alignment with the respective raceways in the
outer member, and corresponding circular rows of rolling elements
each row interposed between the raceway in the outer member and the
raceway in the inner member. In this wheel support bearing
assembly, the following features are employed in accordance with
the teachings of the present invention.
[0010] A sensor cap is secured to an inboard end of the outer
member to close an inboard opening of the outer member. A portion
of the sensor cap, which is made of a synthetic resin, is embedded
with an insert nut with its one open end opening at outer surface
of the sensor cap, and a sensor insertion hole is defined in the
sensor cap in a juxtaposed relation with the insert nut. A sensor
support member carrying a sensor is arranged on an outer surface of
the sensor cap with the sensor inserted into the sensor insertion
hole. This sensor support member has a bolt insertion hole defined
therein, and a sensor fastening bolt is inserted into the bolt
insertion hole and then threaded into the insert nut to fix the
sensor support member to the sensor cap. A pulsar ring cooperable
with the sensor is provided on the inner member so as to confront
the sensor. The sensor cap has a reduced diameter hole defined
therein at a location adjacent a deep end face of the insert nut so
as to communicate between an internally threaded bore of the insert
nut and the inside of the sensor cap. This reduced diameter hole
has an inner peripheral surface formed with a counter surface
confronting the deep end face of the insert nut. A sealing member
having an elasticity is interposed between the counter surface of
the reduced diameter hole and the deep end face of the insert nut
under interference fit therebetween to thereby seal. In other
words, the sealing member is received within the reduced diameter
hole in a state compressed radially inwardly to such an extent as
to allow the sealing member to contact the counter surface of the
reduced diameter hole when nested within the reduced diameter
hole.
[0011] The sensor referred to above may be a rotation sensor for
detecting revolution of the inner member relative to the outer
member.
[0012] According to the present invention, surfaces of contacts of
the internally threaded bore of the insert nut and between the
outer periphery of the insert nut and that portion of the sensor
cap, which is made of the synthetic resin, are communicated with
the inside of the bearing assembly only through the reduced
diameter hole and nowhere in the vicinity of the internally
threaded bore and the sensor fastening bolt is communicated with
the inside of the bearing assembly. The reduced diameter hole
referred to above is sealed in the presence of the sealing member.
For this reason, slight gaps present between the internally
threaded bore of the insert nut, the sensor fastening bolt and the
sensor support member are sealed off from the inside of the bearing
assembly and an undesirable ingress of the foreign matter such as,
for example, muddy water into the inside of the bearing assembly
through those gaps can be prevented by the sealing function of the
sealing member.
[0013] In a preferred embodiment of the present invention, the
sealing member referred to above may be a rubber ball. Material for
the rubber ball may be chosen from the group consisting of nitrile
rubber, fluorocarbon rubber, acrylic rubber and hydrogenated
nitrile rubber. The sealing member in the form of the rubber ball
is convenient in that the sealing member can easily be mounted.
[0014] Where the sealing member is employed in the form of the
rubber ball, the reduced diameter hole represents a hole that forms
an interference allowance (represented by the difference in
diameter between the rubber ball and the diameter of the reduced
diameter hole) with the rubber ball and may be formed in part in a
thick walled portion of the sensor cap, which is positioned at a
location aligned with the deep end face of the insert nut, and in
part in an annular protrusion protruding rearwardly of the thick
walled portion and having an inner peripheral surface thereof
defining the counter surface. Thus, where the annular protrusion is
employed having its inner peripheral surface thereof defining the
counter surface and the reduced diameter hole has an inner surface
that forms the interference allowance with the rubber ball, the
sealing member in the form of the rubber ball can easily be fitted
with a simplified structure and can also provide an excellent
sealing effect.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In any event, the present invention will become more clearly
understood from the following description of preferred embodiments
thereof, when taken in conjunction with the accompanying drawings.
However, the embodiments and the drawings are given only for the
purpose of illustration and explanation, and are not to be taken as
limiting the scope of the present invention in any way whatsoever,
which scope is to be determined by the appended claims. In the
accompanying drawings, like reference numerals are used to denote
like parts throughout the several views, and:
[0016] FIG. 1 is a fragmentary longitudinal sectional view of a
wheel support bearing assembly according to a preferred embodiment
of the present invention;
[0017] FIG. 2 is a similar sectional view showing, on an enlarged
scale, a portion of the wheel support bearing assembly encircled as
at II in FIG. 1;
[0018] FIG. 3 is a fragmentary longitudinal sectional view of the
conventional wheel support bearing assembly; and
[0019] FIG. 4 is a similar sectional view showing, on an enlarged
scale, of a portion of the wheel support bearing assembly encircled
as at IV in FIG. 3.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0020] Hereinafter, a wheel support bearing assembly according to a
preferred embodiment of the present invention will be described in
detail with particular reference to FIGS. 1 and 2. The wheel
support bearing assembly as shown therein is in the form of a dual
row angular contact ball bearing and is particularly intended for
use in rotatably supporting a vehicle driven wheel. It is to be
noted that in the description set forth hereinabove and
hereinafter, the terms "inboard" and "outboard" are a relative term
intended to speak of the direction or orientation with respect to
the transverse sense of an automotive vehicle incorporating the
wheel support bearing assemblies of the present invention, in which
the inboard and outboard sides are close to and remote from the
transverse sense of the automotive vehicle, respectively. For
example, inboard and outboard ends of an elongated element
represent the respective ends of the elongated element close to and
remote from the transverse sense of the automotive vehicle. Hence,
as viewed in FIG. 1, left and right sides of the figure are
interchangeable with the outboard and inboard sides,
respectively.
[0021] The wheel support bearing assembly best shown in FIG. 1 is
utilized to support a vehicle driven wheel rotatably relative to an
automotive body structure and includes a bearing unit 11, which is
made up of a generally tubular outer member 1 having its inner
peripheral surface formed with axially spaced apart raceways 1a, an
inner member 2 generally positioned inside the tubular outer member
1 and having raceways 2a defined therein in alignment with the
associated raceways 1a in the outer member, and a plurality of, for
example, two, rows of rolling elements 3 each row interposed
between the raceways 1a and 2a in the outer and inner members 1 and
2. The raceways 1a and 2a have their respective contact angles so
defined as to achieve a back-to-back alignment. The rolling
elements 3 are in the form of a ball and are operatively retained
by a ball retainer 6 for each row thereof. An annular bearing space
delimited between the outer and inner members 1 and 2 has inboard
and outboard open ends opposite to each other and the outboard open
end of this annular bearing space is sealed by a contact-type
sealing member 7 such as, for example, an oil seal.
[0022] The outer member 1 forms a stationary or non-rotatable
member and is adapted to be secured to the vehicle body structure
through a vehicle body connecting flange (not shown) integral with
the outer member 1. On the other hand, the inner member 2 forms a
rotatable member and is made up of an hub axle 4 having an outboard
end formed with a radially outwardly extending wheel mounting
flange 4a, and an inner race segment 5 press-fitted onto an inboard
end of the hub axle 4 for rotation together therewith. This inner
race segment 5 is fixed axially immovably in position in coaxial
relation with the hub axle 4 by means of a flange-shaped crimped
portion 4b formed in the inboard end of the hub axle 4. The
raceways 2a described as provided in the inner member 2 are in
practice defined in the hub axle 4 and the inner race segment 5,
respectively. Although not shown, the vehicle wheel is firmly
secured to the wheel mounting flange 4a of the hub axle 4 by means
of a plurality of bolts 12 in any manner known to those skilled in
the art.
[0023] The inner race segment 5 forming a part of the inner member
2 has a pulsar ring 9 fitted thereto, which ring 9 forms a
to-be-detected element of a rotation sensor unit 8. On the other
hand, a sensor 10 is mounted on the outer member 1 through a sensor
cap 13 so as to axially confront the pulsar ring 9. This sensor 10
cooperate with the pulsar ring or to-be-detected element 9 to
define the rotation sensor unit 8 for detecting the number of
revolutions of the inner member 2 relative to the outer member
1.
[0024] The pulsar ring 9 is in the form of a cup-like configuration
made up of a disc area 9a and a generally cylindrical wall 9b
protruding axially outwardly from an outer periphery of the disc
area 9a and is secured to the inboard end of the hub axle 4,
particularly the inner race segment 5 with the axially extending
cylindrical wall 9b capped under interference fit onto an outer
periphery of the inboard end of the inner race segment 5. In this
condition, the disc area 9a of the pulsar ring 9 is held in
position intervening between the inboard end of the hub axle 4 and
the sensor cap 13.
[0025] The disc area 9a of the pulsar ring 9 is formed with a
circular row of windows or perforations 14 spaced equidistantly
from each other in a direction circumferentially of the disc area
9a. The sensor 10 referred to above is in the form of a passive
type sensor and is positioned to align with the path of travel of
the windows 14 during the rotation of the inner member 2 relative
to the outer member 1 so that the sensor 10 can detect intermittent
passage of those windows 14 during the rotation of the inner member
2 to thereby provide a rotation detection signal of a frequency
proportional to the number of revolutions of the inner member
2.
[0026] It is to be noted that the pulsar ring 9 may be in the form
of a disc-shaped magnetic encoder such as, for example, a
multipolar magnet having a plurality of opposite north and south
magnetic poles alternating in a direction circumferentially
thereof.
[0027] The sensor cap 13 is also in the form of a cup-like
configuration made up of a disc-shaped end plate 13a and a
generally cylindrical wall 13b protruding axially outwardly from an
outer periphery of the end plate 13a. This sensor cap 13 is formed
of a resin by the use of any known injection molding technique
together with a metallic reinforcement ring 13c and is secured to
the outer member 1 with the axially protruding cylindrical wall 13b
press-fitted into the bore of the outer member 1 to thereby close
an inboard open end of the outer member 1. The metallic
reinforcement ring 13c forming a part of the sensor cap 13 is
inserted within the axially protruding cylindrical wall 13b so as
to occupy an inner peripheral portion thereof, thereby to assist
the interference fit of the cylindrical wall 13b into the bore of
the outer member 1.
[0028] At least the disc-shaped end plate 13a of the sensor cap 13,
which lies in a plane perpendicular to the longitudinal axis of the
bearing assembly is made of a synthetic resin. This disc-shaped end
plate 13a is formed integrally with a mounting boss 28 so as to
protrude in a direction axially thereof, and an insert nut 15 is
embedded within this mounting boss 28 with its one opening end
opening at outer surface of the mounting boss 28. The disc-shaped
end plate 13a is also formed with a sensor insertion hole 16
juxtaposed to the insert nut 15 in the mounting boss 28 for
receiving therein a part of the sensor 10. Specifically, the sensor
10 has a stud end 10a and a base end 10b opposite to the stud end
10a and is received within the sensor insertion hole 16 through a
sleeve 17 that is fixedly inserted into the sensor insertion hole
16 so as to intervene between a peripheral wall defining the sensor
insertion hole 16 and the stud end 10a. An O-ring seal 18 is
mounted on the stud end 10a of the sensor 10 and intervenes between
an inner peripheral surface of the sleeve 17 and an outer
peripheral surface of the stud end 10a of the sensor 10 to thereby
seal a gap therebetween.
[0029] The sensor 10 is fitted to a sensor support member 19
through the base end 10b thereof, which protrudes outwardly from an
outer surface of the disc-shaped end plate 13a of the sensor cap
13. This sensor support member 19 has a bolt insertion hole 20
defined therein, which is disposed adjacent an outer surface of the
disc-shaped end plate 13a of the sensor cap 13 in alignment with an
opening of the insert nut 15. The bolt insertion hole 20 defined in
the sensor support member 19 has a sleeve 21 tightly received
therein. It will readily be seen that when a sensor fastening bolt
22 inserted into the sleeve 21 is threaded into the insert nut 15
rigid with the sensor cap 13, the sensor support member 19 can be
firmly fastened to the disc-shaped end plate 13a of the sensor cap
13.
[0030] The disc-shaped end plate 13a of the sensor cap 13 has a
reduced diameter hole 23 defined therein at a location adjacent a
deep end face (i.e., an outboard end face) 15a of the insert nut 15
so as to extend from an internally threaded bore of the insert nut
15 to an inner surface of the disc-shaped end plate 13a of the
sensor cap 13, that is, completely across a thick walled portion
13aa of the sensor cap 13, particularly an end wall of the mounting
boss 28 then receiving therein the insert nut 15. This reduced
diameter hole 23 has a counter surface 24 defined in an inner
peripheral surface thereof, which surface 24 is opposed to the deep
end face 15a of the insert nut 15.
[0031] A sealing member 25 in the form of a rubber ball having an
elasticity is interposed between the counter surface 24 of the
reduced diameter hole 23 and the deep end face 15a of the insert
nut 15 under interference fit left therebetween, i.e., in a
radially inwardly compressed state, to thereby seal the reduced
diameter hole 23 when the rubber ball 25 nested within the reduced
diameter hole 23 restores to the original spherical shape. Material
for the sealing member, that is, the rubber ball 25 is one selected
from the group consisting of, for example, nitrile rubber,
fluorocarbon rubber, acrylic rubber and hydrogenated nitrile
rubber.
[0032] The inner peripheral surface of the reduced diameter hole 23
represents a generally spherical shape in conformity with the shape
of the sealing member 25. A portion of the disc-shaped end plate
13a of the sensor cap 13, which is generally aligned with the deep
end face 15a of the insert nut 15 is formed with the thick walled
portion 13aa that protrudes axially inwardly (i.e., rearwardly) of
the end plate 13a and an annular protuberance 13ab is provided so
as to protrude rearwardly of the thick walled portion 13aa. The
spherical inner surface of the reduced diameter hole 23, which
defines the counter surface 24, is formed in both of the thick
walled portion 13aa and the annular protuberance 13ab.
[0033] With the wheel support bearing assembly so constructed as
hereinbefore described, surfaces of contacts of the internally
threaded bore of the insert nut 15 and between the outer periphery
of the insert nut 15 and that portion of the sensor cap 13, which
is made of the synthetic resin, are communicated with the inside of
the bearing assembly only through the reduced diameter hole 23 and
nowhere in the vicinity of the internally threaded bore and the
sensor fastening bolt is communicated with the inside of the
bearing assembly. The reduced diameter hole 23 referred to above is
sealed in the presence of the sealing member 25. For this reason,
slight gaps present between the internally threaded bore of the
insert nut 15, the sensor fastening bolt 22 and the sensor support
member 19 are sealed off from the inside of the bearing assembly
and, accordingly, an undesirable ingress of the foreign matter such
as, for example, muddy water into the inside of the bearing
assembly through those gaps can be prevented by the sealing
function of the sealing member 25.
[0034] Also, since the sealing member 25 is employed in the form of
the rubber ball and since the reduced diameter hole 23 represents a
hole having an inner peripheral surface so shaped as to form the
interference allowance with the rubber ball and is formed in part
in the thick walled portion 13aa of the sensor cap 13, which is
positioned at a location aligned with the deep end face 15a of the
insert nut 15, and in part in the annular protrusion 13ab
protruding rearwardly of the thick walled portion 13aa and having
an inner peripheral surface thereof defining the counter surface
24, the sealing member 25 can easily be fitted with a simplified
structure. Also, since the sealing member 25, which is spherical in
shape, is disposed inside the reduced diameter hole 23 under
interference fit, the sealability can be excelled.
[0035] In the practice of the present invention, the reduced
diameter hole 23 has a diameter d that is one half or less than the
outer diameter D of the insert nut 15. However, in view of
limitations imposed on the molding, the diameter d is preferably
1/6 or greater than, and more preferably within the range of 3/7 to
1/4, of the outer diameter D. The diameter d in this embodiment
shown in FIG. 2 is 1/3 of the outer diameter D.
[0036] Although the present invention has been fully described in
connection with the preferred embodiments thereof with reference to
the accompanying drawings which are used only for the purpose of
illustration, those skilled in the art will readily conceive
numerous changes and modifications within the framework of
obviousness upon the reading of the specification herein presented
of the present invention. Accordingly, such changes and
modifications are, unless they depart from the scope of the present
invention as delivered from the claims annexed hereto, to be
construed as included therein.
* * * * *